Black powder catalyst for hydrogen production via autothermal reforming

ABSTRACT

A autothermal reforming catalyst that includes treated black powder (primarily hematite), and a method of treating black powder (e.g., from a natural gas pipeline) to give the treated black powder. An autothermal reformer having the treated black powder as reforming catalyst, and a method of producing syngas with the autothermal reformer.

CROSS REFERENCE TO RELATED PATENT APPLICATION

This application is a divisional of and claims the benefit of priorityto U.S. patent application Ser. No. 17/140,240 filed on Jan. 4, 2021,the contents of which are incorporated by reference herein.

TECHNICAL FIELD

This disclosure relates to hydrogen production via autothermal reformingof hydrocarbon.

BACKGROUND

Hydrogen is commercially produced, such as from fossil fuels. Hydrogenmay be produced, for example, through reforming of hydrocarbons orelectrolysis of water. Hydrogen is produced by coal gasification,biomass gasification, water electrolysis, or the reforming or partialoxidation of natural gas or other hydrocarbons. The produced hydrogencan be a feedstock to chemical processes, such as ammonia production,aromatization, hydrodesulfurization, and the hydrogenation orhydrocracking of hydrocarbons. The produced hydrogen can be a feedstockto electrochemical processes, such as fuel cells.

Carbon dioxide is the primary greenhouse gas emitted through humanactivities. Carbon dioxide (CO2) may be generated in various industrialand chemical plant facilities. At such facilities, the utilization ofCO2 as a feedstock may reduce CO2 emissions at the facility andtherefore decrease the CO2 footprint of the facility. The conversion ofthe greenhouse gas CO2 into value-added feedstocks or products may bebeneficial. The reforming of hydrocarbon (e.g., methane) may utilizeCO2.

The reforming of natural gas is the most prevalent source of hydrogenproduction. Bulk hydrogen is typically produced by the steam reformingof natural gas (methane). Steam reforming includes heating the naturalgas (e.g., to between 500° C. to 1100° C.) in the presence of steam.Conventional catalyst employed includes, for example, nickel, nickelalloys, or magnesium oxide (MgO). This endothermic reaction generates COand H2.

Solid-carbon formation may occur in a reformer reactor vessel. The solidcarbon or carbonaceous material may be labeled as coke. Thus, thesolid-carbon formation may be called coke formation. Deposition of thesolid carbon as carbonaceous depositions on the reforming catalyst canreduce catalyst effectiveness and therefore lower conversion of the feedinto syngas. Solid-carbon formation can lead to degradation of catalystsand cause reactor blockage. Thermodynamically, solid-carbon-formationreaction(s) in the reformer vessel can be a favorable reaction.

SUMMARY

An aspect relates to a method of autothermal reforming hydrocarbon,including reacting the hydrocarbon with carbon dioxide and oxygen viareforming catalyst to generate synthesis gas including hydrogen andcarbon monoxide, wherein the reforming catalyst includes treated blackpowder having hematite.

Another aspect relates to a method of autothermal reforming hydrocarbon,including providing hydrocarbon, carbon dioxide, and oxygen to anautothermal reformer vessel, wherein reforming catalyst includingtreated black powder is disposed in the autothermal reformer vessel. Themethod includes autothermal reforming the hydrocarbon in the autothermalreformer vessel via the reforming catalyst to generate hydrogen andcarbon monoxide, and discharging the hydrogen and carbon monoxide fromthe autothermal reformer vessel.

Yet another aspect relates to a method of preparing a reforming catalystfor autothermal reforming methane, including receiving black powder andapplying heat to the black powder to give heat-treated black powder. Themethod includes applying heat to the heat-treated black powder inpresence of air to give a calcined black powder for autothermalreforming of methane, wherein a majority of the calcined black powder ishematite.

Yet another aspect relates to a reforming catalyst for reforming methanewith carbon dioxide and oxygen, the reforming catalyst having at least70 weight percent of hematite, wherein the hematite is both a supportand active portion of the reforming catalyst, and wherein in reformingof the methane, the hematite being amphoteric advances both cracking ofthe methane and dissociation of the steam.

Yet another aspect is an autothermal reformer including an autothermalreformer vessel having at least one inlet to receive methane, carbondioxide, and steam. The autothermal reformer vessel has a reformingcatalyst including calcined black powder to convert the methane, carbondioxide, and oxygen into syngas. The autothermal reformer vessel has anoutlet to discharge the syngas, wherein the syngas includes hydrogen andcarbon monoxide.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram of a pipe.

FIG. 2 is an x-ray diffraction (XRD) spectra of a sample of treatedblack powder.

FIG. 3 is a diagram of an autothermal reformer for autothermal reforming(ATR) of hydrocarbon.

FIG. 4 is a block flow diagram of a method of ATR of hydrocarbon.

FIG. 5 is a block flow diagram of method of preparing a reformingcatalyst for ATR of hydrocarbon (e.g., CH4).

FIG. 6 is a plot of the percent of H2 in effluent over time for theExample.

DETAILED DESCRIPTION

Some aspects of the present disclosure are directed to collecting andprocessing black powder to give a catalyst (having hematite) that isutilized as reforming catalyst in autothermal reforming (ATR) ofmethane. The catalyst is the processed black powder and thus may belabeled as a derivative of black powder. The processing of the blackpowder may include both heat treatment (e.g., at least 500° C.) andsubsequent calcination (e.g., at least 775° C.). The treatment of theblack powder gives the catalyst having Iron(III) oxide (Fe2O3) alsoknown ferric oxide or hematite. This processing increases the amount ofhematite (Fe2O3) in the black powder. Hematite (Fe2O3) is amphoteric andmay be beneficial for catalysis in ATR of methane into syngas. Aspectsof the present techniques relate to hydrogen production via ATR ofhydrocarbon (e.g., methane) utilizing calcined black powder as thereforming catalyst.

Embodiments may heat treat and calcine black powder to give the treatedblack powder as having predominantly Fe2O3 (amphoteric). The calcinedblack powder may be employed as an ATR catalyst. The amphoteric (acidicbasic) characteristic of the calcined black powder may provide basicsites for carbon dioxide disassociation as well as acidic sites formethane cracking. This may help in diminishing the need for adding orimpregnating metals (precious or non-precious) typically utilized withATR catalysts. In addition, black powder as a waste in the oil and gasindustry is beneficially utilized.

In general, black powder is a solid contaminant often found inhydrocarbon gas pipelines. Black powder is debris in natural-gaspipelines formed by corrosion of the pipeline, such as on the innersurface of inside diameter of the pipe. The black powder may be formedby corrosion of the internal surface of the pipeline wall. The term“black powder” describes regenerative debris formed inside natural gaspipelines due to corrosion of the internal wall of the pipeline. Blackpowder is generally regarded as a chronic nuisance that may be removedfrom the pipeline system, for example, by the use of a separator orcyclone. Black powder is considered a continuing problem as unwantedmaterial removed from valuable process streams via filter bags,separators, or cyclones, and so on. The material may be wet, forexample, having a tar-like appearance. The black powder be a very fine,dry powder. Black powder is primarily composed of iron oxides, silicaand other metal carbonates, hydroxides, and sulfide iron carbonates.Black powder can include mill-like scale, such as hematite (Fe2O3) andmagnetite (Fe3O4). Black powder is a waste present in the natural gasindustry in relatively large amounts. Limited efforts have been exertedto utilize black powder, despite its availability in large amounts atalmost no cost. The black powder can be collected from the pipelines,such as by a separator or from filters employed in upstream portions ofgas refineries. Gas refineries may include natural gas processing plantsor similar processing sites or facilities. The upstream filters (e.g.,coreless filters) may be located before the gas processing plant(refineries) along the pipeline from the wellhead of the gas well (oroil and gas well). Also, these filters may be located at the inlet ofgas processing plant refineries. The black powder may be collected fromthe filter units as the filter units are opened and cleaned, orcollected as dumped nearby the filtration. In present embodiments, theblack powder as retrieved may be transported to the treatment.

Black powder is primarily found in gas pipelines between the wellheadand the natural gas processing plant. Black powder may be generallyabsent from gas pipelines downstream of the natural gas processing plantbecause acid gas (hydrogen sulfide and carbon dioxide), mercury, water,and gas condensate will have generally been removed from the naturalgas. The removal of these contaminants reduces occurrence of blackpowder downstream of the natural gas processing plant.

The ATR is a process that may utilize methane (CH4), carbon dioxide(CO2), and oxygen (O2) as reactants to produce synthesis gas (syngas)with the aid of catalyst. The syngas may include hydrogen (H2) andcarbon monoxide (CO). Autothermal reforming (ATR) may be a term todescribe a type of methane reforming that utilizes both CO2 and O2.Thus, ATR may be characterized as combining dry reforming and partialoxidation into a single reactor in some implementations. The ATRreaction may be 2CH4+CO2+O2⇄3H2+3CO+H2O. More H2 (if desired), alongwith carbon dioxide (CO2), may be produced through the water gas-shiftreaction CO+H2O⇄CO2+H2 in addition to the ATR. However, the ATR may beimplemented, for example, where CO is a more desired product than H2,and therefore the water gas-shift reaction would not be implemented.

ATR is not as common as steam reforming. ATR is sometimes employed inprocesses that benefit from a high proportion of CO versus H2 in theproduced syngas. The thermodynamics of ATR may be similar to those ofsteam reforming. A difference of ATR compared to steam reforming may bethe tendency for coking in ATR, increased by a lack of steam to removecarbon deposits. In some applications, such as mixed reforming orbi-reforming (a combination of steam reforming and dry reforming), steamis added for effective reduction or removal of coke. However, again, ATRrelying on O2 may lack this benefit of steam addition. Because cokingcan quickly deactivate nickel (Ni catalysts), ruthenium (Ru) and rhodium(Rh) are catalysts sometimes utilized in ATR of methane. However, Ru andRh are expensive. In contrast, embodiments herein employ treated blackpowder as reforming catalyst for the ATR of CH4.

Black powder that is heat treated and calcined may be employed as acatalyst for ATR. The heat-treated/calcined black powder may beprimarily Fe2O3. The Fe2O3 being amphoteric may promote the simultaneousoccurrence of CO2 dissociation, CH4 cracking, and oxidation of carbonspecies on the catalyst surface without the need to add or impregnateprecious or non-precious metals nor the prerequisite to have specificbasic sites (e.g., mainly for CO2 dissociation) on the catalystsubstrate (support). Thus, calcined black powder may be beneficial as acatalyst for ATR because black powder as calcined in an air environmentmainly consists (greater than 50 weight percent) of Fe2O3 (amphoteric)that can provide for contemporaneous CH4 cracking and CO2 dissociationin the ATR reactor. Again, the treated black-powder catalyst havingprimarily amphoteric Fe2O3 may allow such without the need to add orimpregnate metals (precious or non-precious) nor the need to havespecific basic sites on the substrate of the catalyst. The term“amphoteric” may refer to a compound, such as a metal oxide orhydroxide, able to react both as a base and as an acid. Theimplementation of black powder catalyst in ATR may facilitate use ofgreenhouse gases (CH4 and CO2) and waste material (black powder) toproduce the valuable commodity syngas (CO and H2).

FIG. 1 is a pipe 100 (conduit) that may be piping or pipeline in ahydrocarbon gas (natural gas) system. The pipe 100 has a pipe wall 102having a wall thickness. Black powder 104 is collected along the innersurface 106 of the pipe 100. The inner surface 106 is the internalsurface of the inside diameter of the pipe 100. As indicated, blackpowder is regenerative and formed inside natural gas pipelines becauseof corrosion of the inner surface 106. Black powder forms throughchemical reactions of iron (Fe) in ferrous pipeline steel with condensedwater containing oxygen, CO2, and other gases. Black powder is mainlycomposed of iron hydroxides, iron oxides, and iron carbonates. Thephrase “black powder” refers to the residue (material) that is formedalong inner surface of pipelines as a natural waste product as a resultof corrosion and includes metal oxide. Again, black powder can becollected from upstream filters employed in gas refineries. For manyyears, pipeline companies have observed the presence of black powder andits effects, but have viewed black powder generally only as an annoyanceand therefore have done little to understand or use black powder.Instead, pipeline companies have primarily sought ways of removing theblack powder from the pipelines. There are several approaches to removethe black powder, such as via separators and cyclones, where the blackpowder-laden gas passes through these devices and the black powderparticles are physically knocked out of the gas stream. For instance,the black powder particles are removed from the gas stream and attach tothe walls of the device (e.g., separator, cyclone) where they fall andare collected at the bottom in a collection media. Pipeline companiesgenerally do not recognize a beneficial use for the black powder.Throughout the world, black powder from gas pipelines exists in largeamounts, and is thus readily available at a very low cost due to itsperceived lack of value. Black powder is typically discarded as waste.As mentioned, in many cases, black powder is regenerative debris that isformed inside natural gas pipelines as a result of corrosion of theinternal walls of the pipeline. Black powder can also be collected fromupstream filters or filter bags used in gas refineries.

The typical major mineral composition of black powder without treatmentis primarily iron oxide. The iron oxide includes magnetite (Fe3O4) andhematite (Fe2O3). The black powder also includes quartz (SiO2) and mayinclude, metal carbonates, metal hydroxides, and sulfide ironcarbonates. The Table below gives the elemental composition of a sampleof example black powder “as is” (as collected) and also after the sampleas “heat treated” (heat treatment at 500° C. for 3 hours). The heattreatment at 500° C. removes carbon associated with the metals, asindicated in the Table. The elements listed in the Table are carbon (C),oxygen (O), magnesium (Mg), silicon (Si), sulfur (S), chlorine (Cl),calcium (Ca), iron (Fe), and manganese (Mn). The composition is given inweight percent (wt %).

TABLE Elemental Composition of Black Powder *Black **Black Powder Powder“as is” “heat treated” Element (wt %) (wt %) C 20.85 0 O 29.29 25.39 Mg1.07 1.08 Si 0.41 0.48 S 1.88 2.63 Cl 2.10 1.53 Ca 1.23 1.88 Fe 43.0665.7 Mn non-detectable 1.32 Total 100 100 *as collected **aftersubjected to 500° C. for 3 hours

The sample of the heat-treated black powder was then subjected toadditional heat treatment that was air calcination at about 775° C. for4 hours. Particles of the resulting powder as analyzed by x-raydiffraction (XRD) were mainly hematite (Fe2O3) as shown in the XRDspectra in FIG. 2 .

FIG. 2 is XRD spectra 200 of a sample of the black powder after theblack powder was (1) heat treated at 500° C. for 3 hours and (2)subjected to calcination in air at 775° C. for 4 hours. The scatteringangle (or diffraction angle) is 2-theta in degrees. The spectra 200indicates phase identification of black powder after being heat treatedfirst at 500° C. for 3 hours and then at 775° C. for 4 hours. The heattreatment at both temperatures was performed under air. The heattreatment at 500° C. removes carbon (C). The heat treatment at 775° C.can be characterized as calcination. The calcination at 775° C. maypromote further C removal and oxidize the metals present to a higheroxidation state. The x-ray diffraction of the calcined powder sampleresulted in a pattern characterized by reflections (peaks in intensity)at certain positions. FIG. 2 indicates the minerals in the sample. Thesymbols 202 note the peaks for the primary mineral in the sample ofcalcined black powder, which is hematite. The symbols 204 note the peaksfor the secondary mineral in the sample, which is iron oxide Fe507. Thesymbols 202 locate the spectra of hematite, which is the most intensepeaks over the other iron form. The spectra 200 indicates that amajority of the calcined black-powder sample is hematite. In particular,the spectra 200 indicates that at least 80 wt % of the air-calcinedblack powder is hematite. Calcined black powder as described herein mayhave at least 50 wt % hematite, at least 60 wt % hematite, at least 70wt % hematite, at least 80 wt % hematite, or at least 90 wt % hematite.

Black powder as collected from a natural gas pipeline system may haveprimarily magnetite and hematite. The black powder may be heat treated(e.g., at 500° C.) to remove carbon (including carbon deposition) fromthe black powder. This heat-treated black powder may be subjected tocalcination (e.g., at 775° C.). For the calcination performed in aninert atmosphere, the calcination may drive formation of magnetite. Incontrast, for the calcination performed in an air atmosphere, thecalcination may drive formation of hematite. As for minerals in theair-calcined black powder, hematite may approach 100 wt %. As for theoverall composition of the air-calcined black powder, the hematite is atleast 50 wt % and can be at least 80 wt % or at least 90 wt %.

FIG. 3 is an autothermal reformer 300 (including an autothermal reformervessel 302) to convert hydrocarbon (e.g., CH4) in presence of CO2, O2,and reforming catalyst 304 into syngas. The autothermal reformer 300 maybe an autothermal reformer system. The autothermal reformer 300 orautothermal reformer vessel 302 may be characterized as an autothermalreformer reactor or autothermal reformer reactor vessel, respectively,for the ATR of hydrocarbon (e.g., CH4) to give syngas. A reformingcatalyst 304 that is air-calcined black powder (e.g., see spectra 200 ofFIG. 2 ), as discussed above, is disposed in the autothermal reformervessel 302. The reforming catalyst 304 as calcined black powder may beblack powder (e.g., collected from a natural-gas pipeline system) thatis heat treated at a temperature of at least 500° C. for at least 3hours and calcined at a temperature of at least 775° C. in presence ofair for at least 4 hours. A majority of the calcined black powder ishematite. At least 50 wt % of the reforming catalyst 304 may behematite.

The autothermal reformer 300 may be, for instance, a fixed-bed reactoror a fluidized bed reactor. The autothermal reformer vessel 302 may be afixed-bed reactor vessel having the reforming catalyst 304 in a fixedbed. In implementations, the fixed-bed reactor vessel may be amulti-tubular fixed-bed reactor. The autothermal reformer vessel 302 maybe a fluidized-bed reactor vessel that operates with a fluidized bed ofthe reforming catalyst 304.

The operating temperature of the autothermal reformer 300 (the operatingtemperature in the autothermal reformer vessel 302) may be, for example,in the ranges of 500° C. to 1100° C., 500° C. to 1000° C., 500° C. to900° C., at least 500° C., less than 1000° C., or less than 900° C. Thisautothermal reforming reaction may be exothermic due to the oxidation.The autothermal reformer vessel 302 (autothermal-reformer reactorvessel) may have a jacket for heat transfer and temperature control. Inoperation, a heat transfer fluid (e.g., heating medium) may flow throughthe jacket for temperature control of the autothermal reformer 300including the autothermal reformer vessel 302. Heat transfer maygenerally occur from the heat transfer fluid in the jacket to the ATRreaction mixture (process side of the autothermal reformer vessel 302).In other embodiments, electrical heaters may provide heat for the ATRreaction. The electrical heaters may be disposed in the autothermalreformer vessel 302 or on an external surface of the autothermalreformer vessel 302. In yet other embodiments, the autothermal reformervessel 302 may be disposed in a furnace (e.g., a direct fired heater) toreceive heat from the furnace for the ATR reaction and for temperaturecontrol of the autothermal reformer 300. Other configurations of heattransfer and temperature control of the autothermal reformer 300 areapplicable. The operating pressure in the autothermal reformer vessel302 may be, for example, in the range of 1 bar to 28 bar, or less than30 bar. In some implementations, the operating pressure may be greaterthan 30 bar to provide additional motive force for flow of thedischarged syngas 310 to downstream processing.

In operation, the autothermal reformer vessel 302 may receive feed thatincludes hydrocarbon 306, carbon dioxide 308, and oxygen 309. While thehydrocarbon 306, carbon dioxide 308, and oxygen 309 are depicted asintroduced as a combined stream into the autothermal reformer vessel302, the hydrocarbon 306, carbon dioxide 308, and oxygen 309 may beintroduced separately to the autothermal reformer vessel 302 in someimplementations. The hydrocarbon 306 may generally include CH4. Forexample, the hydrocarbon 306 stream may be or include natural gas. Inother examples, the hydrocarbon 306 includes CH4 but is not anatural-gas stream. The hydrocarbon 306 may be a process stream or wastestream having CH4. The hydrocarbon 306 may include CH4, propane, butane,and hydrocarbons having a greater number of carbons. The hydrocarbon 306may include a mixture of hydrocarbons (e.g., C1 to C5), liquefiedpetroleum gas (LPG), and so on. Additional implementations of thehydrocarbon 306 (e.g., having CH4) are applicable. In some embodiments,the oxygen 309 may be air. In certain embodiments, the carbon dioxide308 may instead be steam for the ATR, and with the calcined black powderas the reforming catalyst 304 as applicable.

The ATR of the hydrocarbon 306 may give syngas 310 having H2 and CO. TheATR reaction via the catalyst 304 in the autothermal reformer vessel 302may be represented by 2CH4+CO2+O2⇄3H2+3CO+H2O. The molar ratio of H2 toCO in the syngas 310 based on the ideal thermodynamic equilibrium is 1:1but in practice can be different than 1:1. Unreacted CH4 may dischargein the syngas 310 stream. In some implementations, unreacted CH4 may beseparated from the discharged syngas 310 and recycled to the autothermalreformer vessel 302.

Moreover, the generated CO may be subjected to a water-gas shiftreaction to obtain additional H2, as given by CO+H2O⇄CO2+H2. Thewater-gas shift reaction may be performed in the autothermal reformervessel 302. The reforming catalyst 304 may promote the water-gas shiftreaction if implemented. The water-gas shift reaction may instead beimplemented downstream. The discharged syngas 310 may be processed toimplement the water-gas shift reaction downstream of the autothermalreformer vessel 302. Utilization of the water-gas shift reaction,whether performed in the autothermal reformer vessel 302 or downstreamof the autothermal reformer vessel 302, may be beneficial to increasethe molar ratio of H2/CO in the syngas 310 for downstream processing ofthe syngas 310. The downstream processing may include, for example, aFischer-Tropsch (FT) reactor or other processing. In certainimplementations, the molar ratio of H2/CO may also be increased with theaddition of supplemental H2 (e.g., from water electrolysis) to thedischarged syngas 310.

The autothermal reformer 300 system may include feed conduits for thehydrocarbon 306, carbon dioxide 308, and oxygen 309, and a dischargeconduit for the syngas 310. The autothermal reformer vessel 302 may be,for example, stainless steel. The autothermal reformer 302 vessel hasone or more inlets to receive the feeds (e.g., 306, 308, 309). Theinlet(s) may be, for example, a nozzle having a flange or threaded(screwed) connection for coupling to a feed conduit conveying the feedto the autothermal reformer vessel 302. The vessel 302 may have anoutlet (e.g., a nozzle with a flanged or screwed connection) for thedischarge of produced syngas 310 through a discharge conduit fordistribution or downstream processing. The flow rate (e.g., volumetricrate, mass rate, or molar rate) of the feed 306, 308, 309 may becontrolled via at least one flow control valve (disposed along a supplyconduit) or by a mechanical compressor, or a combination thereof. Theratio (e.g., molar, volumetric, or mass ratio) between the hydrocarbon306, carbon dioxide 308, and oxygen 309 may be adjusted by modulating(e.g., via one or more control valves) at least one of the flow rates ofthe streams. The ratio may be based on CH4 or natural gas in thehydrocarbon 306. Lastly, it should be noted that the present calcinedblack-powder catalyst (reforming catalyst 304) may be applicable formixed-steam CO2 reforming (MSCR), steam reforming, bi-reforming, dryreforming alone, and other types of reforming of methane.

An embodiment is an autothermal reformer including an autothermalreformer vessel. The autothermal reformer vessel has at least one inletto receive methane, CO2, and O2. The autothermal reformer vessel has areforming catalyst disposed in the vessel to convert the methane, CO2,and O2 into syngas. The reforming catalyst includes or is calcined blackpowder. The reforming catalyst having or as the calcined black powdermay be at least 50 wt % hematite. The autothermal reformer vessel has anoutlet to discharge the syngas, wherein the syngas includes H2 and CO.The autothermal reformer vessel may be a fixed-bed reactor vessel havingthe reforming catalyst in a fixed bed. If so, the fixed-bed reactorvessel may be a multi-tubular fixed-bed reactor. The autothermalreformer vessel may be a fluidized-bed reactor vessel to operate with afluidized bed of the reforming catalyst.

FIG. 4 is a method 400 of ATR of hydrocarbon. The hydrocarbon mayinclude CH4 and can be or include natural gas. The hydrocarbon may be aprocess stream or waste stream having CH4. The hydrocarbon may includeCH4, propane, butane, and hydrocarbons having a greater number ofcarbons.

At block 402, the method includes providing the hydrocarbon (e.g.,including CH4), CO2, and O2 an autothermal reformer (e.g., to anautothermal reformer vessel). Reforming catalyst that is or includestreated black powder (processed black powder) is disposed in theautothermal reformer vessel. The treated black powder may be calcinedblack powder, as discussed. The reforming catalyst may be the presentreforming catalyst as discussed above and as described in FIG. 5 .

At block 404, the method include ATR of the hydrocarbon in theautothermal reformer via the reforming catalyst to generate H2 and CO.The ATR involves reacting the hydrocarbon (e.g., including CH4) with theCO2 and the O2 via the treated black powder as the reforming catalyst.The method may include providing heat to the autothermal reformer (e.g.,to the autothermal reformer vessel) for the ATR. Heat may be provided byexternal electrical heaters residing on the surface of the autothermalreformer vessel. Heat may be provided by situating the autothermalreformer vessel in a furnace. Other techniques for providing heat (orcooling) to the autothermal reformer are applicable.

The reforming catalyst having amphoteric hematite may beneficiallyprovide in the ATR for both methane cracking and CO2 dissociation. Theamphoteric tendency of hematite may allow for the dissociation of waterand cracking of methane. Oxidation of carbon species on the catalystsurface may also be realized in the ATR reaction. The hematite beingamphoteric (able to react both as a base and as an acid) may aid orpromote methane cracking, CO2 disassociation, and oxidation of carbonspecies on its surface.

At block 406, the method includes discharging the H2 and CO from theautothermal reformer (e.g., from the autothermal reformer vessel). Thedischarged stream having the H2 and CO may be labeled as syngas. Thesyngas may be sent to transportation or distribution. The syngas may besent to downstream processing.

An embodiment is a method of ATR of hydrocarbon, such as CH4. The methodincludes reacting the hydrocarbon with CO2 and O2 via reforming catalystto generate syngas including H2 and CO. The reforming catalyst is orincludes treated black powder that includes hematite. The hematite maybe at least 50 wt % of the treated black powder. The treated blackpowder may be black powder from a natural gas pipeline and that issubjected to heat to give the treated black powder. The treated blackpowder may include black powder subjected to heat treatment at atemperature of at least 500° C. for at least 3 hours. The treated blackpowder may be black powder collected from a natural-gas pipeline systemand that is subjected to heat in presence of air to give the treatedblack powder. The treated black powder may include calcined blackpowder. The treated black powder may include black powder subjected toheat treatment at a temperature of at least 775° C. in presence of airfor at least 4 hours, and wherein this heat treatment includes aircalcination of the black powder. The treated black powder may be orinclude black powder subjected to heat treatment at a temperature of atleast 500° C. to remove carbon from the black powder and then subjectedto air calcination at a temperature of at least 775° C. to give calcinedblack powder as the treated black powder.

FIG. 5 is a method 500 of preparing a reforming catalyst for ATR ofhydrocarbon (e.g., CH4). At block 502, the method includes collectingblack powder. Black powder may be collected as discussed above. Theblack powder may be collected (removed) from a natural-gas pipelinesystem. The natural-gas pipeline system may include a natural gaspipeline(s) including piping, mechanical compressors, filters,separators, etc.

At block 504, the method includes receiving black powder. The blackpowder may be received at a location or facility to treat (e.g., heattreat, calcine, etc.) the black powder. The receiving of the blackpowder comprises may involve receiving the black powder collected from anatural-gas pipeline system.

At block 506, the method includes applying heat to the black powder toremove carbon (e.g., carbon deposition) from the black powder. The blackpowder received may be placed, for example, in an industrial oven (e.g.,industrial-scale heat regenerator) to heat the black powder. Theapplication of the heat may involve applying the heat at a temperatureof at least 500° C. for at least 3 hours to remove the carbon from theblack powder. The applying of heat to the black powder to remove carbonfrom the black powder gives a heat-treated black powder. This applyingof heat for the Example below was applied in the laboratory with atypical oven that was a muffle furnace.

At block 508, the method includes calcining the black powder in presenceof air to give calcined black powder as the reforming catalyst. Thecalcined black powder generally includes hematite. The calcining theblack powder may involve calcining the heat-treated black powder (block506) in the presence of air to give the calcined black powder as thereforming catalyst. The calcining may involve applying heat to the blackpowder in the presence of air at a temperature of at least 775° C. forat least 4 hours to give the calcined black powder as the reformingcatalyst, wherein the hematite is at least 50 wt % of the calcined blackpowder. An example of equipment to subject the heat-treated black powderto calcination at about 775° C. or greater for at least four hours is avessel in a furnace. In some implementations, the calciner is a steelcylinder having the black powder in an air atmosphere in the steelcylinder, and the steel cylinder rotates in a furnace to heat the blackpowder to about 775° C. or greater (in the air atmosphere inside thecylinder) for at least four hours. Calcination may be heating to hightemperatures in air or oxygen. Calcination may be referred to as“firing” or “fired.” Calcining may remove unwanted volatiles from amaterial and convert a material into a more stable, durable, or harderstate. In present embodiments, example conditions of the calcinationinclude calcining the black powder in air at a temperature in a range of700° C. to 800° C. for at least 4 hours. The main compound (e.g., up to90 wt %, or at least 90 wt %) of the air-calcined black powder may beFe2O3. The remainder of the air-calcined black powder may include smallamounts or trace elements of other oxides, such as other iron oxides orsilicon oxide (SiO2). In some implementations, SiO2 may dominate theremainder of air-calcined black powder. The mineral SiO2 is not listedon FIG. 2 because SiO2 was below the detection limit of the used XRDdevice. However, the SiO2 present in the FIG. 2 sample was detected byx-ray fluorescence (XRF) analysis.

At block 510, the method includes supplying the calcined black powderformed in block 508 as the reforming catalyst for ATR of methane. Thecalcined powder may be removed from the calcination equipment (e.g.,vessel) and transported to a facility that autothermal reforms methane.The calcined black powder as reforming catalyst may be placed into anautothermal-reformer reactor vessel.

An embodiment is of preparing a reforming catalyst for ATR of methane.The method includes receiving black powder and applying heat to theblack powder to give heat-treated black powder. The applying of heat tothe black powder may involve applying the heat at a temperature of atleast 500° C. to give the heat-treated black powder. The method includesapplying heat to the heat-treated black powder in presence of air togive a calcined black powder, wherein a majority of the calcined blackpowder is hematite. The applying of heat to the heat-treated blackpowder may involve applying the heat to the heat-treated black powder ata temperature of at least 775° C. in the presence of air to give thecalcined black powder. The reforming catalyst may be or include thecalcined black powder.

Example

In the laboratory, the performance of the present heat-treated/calcinedblack powder (primarily hematite) to generate syngas (including hydrogenproduction) in ATR of methane was compared to performance of aconventional reforming catalyst having the universal basic catalystsubstrate of MgO to generate syngas (including hydrogen production) inATR of methane. The MgO is both a support and the active catalyst. TheATR performance of the present treated black powder versus the ATRperformance of the conventional MgO were compared at the same conditionsof ATR. The ATR conditions included 750° C., 14 bar, and a gas hourspace velocity (GHSV) of 3517 h⁻¹.

FIG. 6 depicts results of the Example comparison, which show a betterperformance by the heat-treated/calcined black powder having primarilyFe2O3 (amphoteric) as compared to the non-amphoteric (solely basic) MgO.FIG. 6 is a plot of the percent (mol %) of H2 in the effluent over time(hours). The time was the experiment time of the ATR in the laboratory.The curve 602 is the mol % H2 in the effluent with the reformingcatalyst as the heat-treated/calcined black powder. The curve 604 is themol % H2 in the effluent with the reforming catalyst as the MgO.

The ATR in the Example laboratory evaluation was performed in aMicroactivity Effi microreactor (compact reactor) system available fromPID Eng & Tech (Madrid, Spain) having Micromeritics Instrument Corp. asparent corporation. The microreactor allows operation at pressures up to100 bars. In the Example, 3 milliliters (ml) of the prepared blackpowder was loaded on the microreactor with a diameter of 9 millimeter(mm) Hastelloy tube and placed inside an electrical furnace. Theprepared black powder (FIG. 2 ) was the black powder subjected to heatat 500° C. for 3 hours and then calcined at 775° C. for 4 hours. In theelectrical furnace, the prepared black powder was reduced with H2 andnitrogen (N2) at 750° C. for 6 hours before the ATR reaction wasstarted. This reduction of the catalyst may make the catalyst moreactive for the steam reforming reaction. Then, a mixture of CH4, CO2,air, and N2 were fed to the microreactor. The N2 was fed into themicroreactor in order to give the GHSV of 3517 h⁻¹. The treatedblack-powder catalyst was gradually pressurized and tested at 14 bar and750° C. while feeding the mixture of CH4, CO2, air, and N2. The same wasperformed for the MgO (3 ml) catalyst support at the same conditions aswell. Testing for each was performed for about 7 hours. The produced gaswas analyzed by the gas chromatography (GC, Agilent 7890B) equipped witha thermal conductivity detector (TCD) and a flame ionization detector(FID). Before analysis, water in the gas was removed with a liquid/gasseparator and a moisture trap. The concentrations of H2 were determinedwith the TCD. The mol composition from the GC was convertedquantitatively based on the amount of N2 in the produced gas.

The Fe2O3 has an amphoteric characteristic (acidic-basic), which maytrigger its use as a catalyst in ATR. Because the Fe2O3 can providebasic sites for CO2 dissociation as well as acidic sites for methanecracking, the need for adding or impregnating precious or non-preciousmetal be avoided in implementations. Behavior of different support typesof reforming catalysts in the ATR of methane into syngas may becompared. Amphoteric support catalysts, such as catalyst that is Fe2O3or the present treated (processed) black powder having primarily Fe2O3,the catalyst may provide for (allows) CH4 cracking and CO2 dissociationthat may occur contemporaneously or simultaneously in the ATR. Incontrast, acidic support catalysts (e.g., silicon oxide or SiO2) mayprovide for (allow) CH4 cracking but generally not CO2 dissociation inthe ATR. Basic support catalysts (e.g., MgO) may provide for (allows)CO2 dissociation but generally not CH4 cracking in the ATR. Iron groupsconsisting of Ni, Co, and Fe possess a high activity toward hydrocarboncracking, with Fe being the lowest activity among the group. However,again, the Fe2O3 being amphoteric may avoid the need to add orimpregnate precious or non-precious metals to the catalyst. Theair-calcined black powder as a catalyst for ATR may be advantageousbecause it mainly consists of the amphoteric (acidic and basic) Fe2O3,which may generally allow for the simultaneous occurrence of methanecracking and CO2 dissociation without the need to add/impregnateprecious or non-precious metals nor the need to have specific basicsites on the substrate.

An embodiment is a reforming catalyst for reforming methane with CO2 andO2. The reforming catalyst includes or is calcined black powder that isblack powder heat treated at a temperature of at least 500° C. for atleast 3 hours and calcined at a temperature of at least 775° C. inpresence of air for at least 4 hours. The black powder is from a naturalgas pipeline. A majority of the calcined black powder is hematite. Thehematite may be both a support and active portion of the reformingcatalyst. The hematite being amphoteric may advance both cracking of themethane and dissociation of the CO2.

Another embodiment is a reforming catalyst for reforming methane (e.g.,ATR of methane) with CO2 and O2. The reforming catalyst has at least 70wt % (or at least 80 wt %) of hematite. The hematite is both a supportand catalytic active portion of the reforming catalyst. The hematitebeing amphoteric advances both cracking of the methane and dissociationof the CO2 in the ATR of the methane. The reforming catalyst may be orinclude calcined black powder having the hematite. The calcined blackpowder is black powder heat treated at a temperature of at least 500° C.for at least 3 hours and calcined at a temperature of at least 775° C.in presence of air for at least 4 hours. The black powder is from anatural gas pipeline.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the disclosure.

What is claimed is:
 1. A method of preparing a reforming catalyst forautothermal reforming methane, comprising: receiving black powder;applying heat to the black powder to remove carbon from the blackpowder; and calcining the black powder in presence of air to givecalcined black powder as the reforming catalyst for the autothermalreforming of methane, wherein the calcined black powder compriseshematite.
 2. The method of claim 1, comprising collecting the blackpowder from a natural-gas pipeline system.
 3. The method of claim 1,wherein receiving the black powder comprises receiving the black powdercollected from a natural-gas pipeline system, wherein applying heat tothe black powder to remove carbon from the black powder gives aheat-treated black powder, and wherein calcining the black powdercomprises calcining the heat-treated black powder in the presence of airto give the calcined black powder as the reforming catalyst.
 4. Themethod of claim 1, wherein applying heat comprises applying the heat ata temperature of at least 500° C. for at least 3 hours to remove thecarbon from the black powder.
 5. The method of claim 1, wherein thecalcining comprises applying heat to the black powder in the presence ofair at a temperature of at least 775° C. for at least 4 hours to givethe calcined black powder as the reforming catalyst, and wherein thehematite is at least 50 weight percent of the calcined black powder. 6.A reforming catalyst for autothermal reforming of methane with carbondioxide and oxygen prepared according to the method of claim
 1. 7. Thereforming catalyst according to claim 6, wherein the reforming catalystcomprises at least 70 weight percent of hematite, wherein the hematiteis both a support and active portion of the reforming catalyst, andwherein the hematite being amphoteric advances both cracking of themethane and dissociation of the carbon dioxide in the autothermalreforming (ATR) of the methane.
 8. The reforming catalyst according toclaim 6, wherein the reforming catalyst comprises calcined black powdercomprising the hematite.
 9. The reforming catalyst according to claim 8,wherein the calcined black powder is black powder heat treated at atemperature of at least 500° C. for at least 3 hours and calcined at atemperature of at least 775° C. in presence of air for at least 4 hours,the black powder from a natural gas pipeline.